This invention relates to internal combustion engines using marine cooling water and more particularily to mechanism for maintaining normal water flow in an intake system having a filter.
Marine craft such as pleasure boats, yachts, fishing boats and other commercial craft using an inboard internal combustion engine for main propulsion and auxiliary purposes, use sea water for cooling the engine. Generally the cooling of the engine is accomplished by pumping the water by means of a pump associated with the engine from an inlet opening in the bottom of the hull through a water inlet conduit, through the engine cooling manifold and thence back to the sea through an exhaust conduit.
Because such craft usually ply river and lake waters having substantial natural weed growth, algae, mud, silt, leaves and the like as well as unnatural debris such as pieces of sheet plastic, rags, paper and the like, it is common practice to provide a relatively coarse strainer at the water inlet opening in the hull to prevent the entry of coarse materials into the intake conduit and further to provide a filter in the water intake conduit between the engine water pump and the filter to prevent the entry of relatively small size materials into the pump and cooling manifold of the engine.
In the typical small boat installation currently in use it is necessary to stop the engine and to manually disassemble the filter unit and clean the filter element manually when the engine overheats due to filter clogging. If the overheating is due to the clogging of the strainer at the hull inlet it is often necessary to clean the strainer from the under side of the boat. In some installations a pair of filters is installed in parallel in the inlet conduit so that the engine may be alternately operated on one of the filters while the other is cleaned manually. It has been proposed to insert a tube in the strainer at the hull and subject it to a fluid blast in response to a partial vacuum condition developed in the water intake conduit due to clogging of the strainer. This approach however, has not been applied to filter cleaning.